Catalyst loading method and method for preparation of butadiene by using same

ABSTRACT

The present specification relates to a method comprising: (A) mixing a ferrite-based catalyst molded article with diluent material particles; and (B) adding the mixture to a catalyst reactor, and a method for preparing butadiene using the same.

The present application is a National Phase entry pursuant to 35 U.S.C.§ 371 of International Application No. PCT/KR2019/001213 filed Jan. 29,2019, and claims priority to and the benefit of Korean PatentApplication No. 10-2018-0018419 filed in the Korean IntellectualProperty Office on Feb. 14, 2018, the entire contents of which areincorporated herein by reference.

FIELD

The present specification relates to a method for filling a catalyst anda method for preparing butadiene using the same.

BACKGROUND

1,3-butadiene is an intermediate of petroleum chemical products, anddemands for 1,3-butadiene, and the value thereof, are graduallyincreasing globally. 1,3-butadiene has been prepared by using naphthacracking, the direct dehydrogenation reaction of butene, oxidativedehydrogenation reaction of butene, and the like.

The oxidative dehydrogenation reaction of butene is a reaction in whichbutene and oxygen react with each other in the presence of a metal oxidecatalyst to produce 1,3-butadiene and water, and has a thermodynamicallyvery favorable advantage because stable water is produced. Further,since the oxidative dehydrogenation reaction of butene is an exothermicreaction unlike the direct dehydrogenation reaction of butene,1,3-butadiene may be obtained at high yield even at low reactiontemperature as compared to the direct dehydrogenation reaction. Theoxidative dehydrogenation reaction of butene may become an effectivesingle production process capable of satisfying the demands for1,3-butadiene because an additional heat supply is not required.

The metal oxide catalyst is generally synthesized by a precipitationmethod. In particular, when a ferrite-based catalyst is used as a metaloxide catalyst, the ferrite-based catalyst generates heats, therebyincreasing the COx selectivity and decreasing the butadiene selectivity.Accordingly, studies on controlling exotherm and simultaneouslycontrolling the hot spot movement of the catalyst have been continuouslyconducted.

SUMMARY

The present specification provides a method for filling a catalyst and amethod for preparing butadiene using the same.

An exemplary embodiment of the present specification provides a methodcomprising:

(A) mixing a ferrite-based catalyst molded article with diluent materialparticles to form a mixture; and

(B) adding the mixture of the ferrite-based catalyst molded article andthe diluent material particles to a catalyst reactor.

Another exemplary embodiment of the present specification provides amethod for preparing butadiene, the method comprising:

adding the mixture to a catalyst reactor according to theabove-described method; and

preparing butadiene by subjecting a raw material comprising butene to anoxidative dehydrogenation reaction in the catalyst reactor.

Further, an exemplary embodiment of the present specification provides acatalyst reactor which contains a mixture of a ferrite-based catalystmolded article and diluent material particles.

A method according to an exemplary embodiment of the presentspecification may simultaneously control a hot spot movement rate of acatalyst within a range capable of controlling exotherm caused by acatalyst reaction during an oxidative dehydrogenation reaction ofbutene, thereby securing the stability of the reaction and reducingcosts caused by an increase in reaction temperature.

In addition, the hot spot movement rate may be decreased by controllingthe concentration of a catalyst as compared to a diluent material in asection of a catalyst reactor where a reaction starts.

DETAILED DESCRIPTION

Hereinafter, the present specification will be described in more detail.

In the present specification, the ‘yield (%)’ is defined as a valueobtained by dividing the weight of 1,3-butadiene as a product of anoxidative dehydrogenation reaction by the weight of butene (BE) as a rawmaterial. For example, the yield may be represented by the followingequation.Yield (%)=[(the number of moles of 1,3-butadiene produced)/(the numberof moles of butene supplied)]×100

In the present specification, the ‘conversion rate (%)’ refers to a rateat which a reactant is converted into a product, and for example, theconversion rate of butene may be defined by the following equation.Conversion rate (%)=[(the number of moles of butene reacted)/(the numberof moles of butene supplied)]×100In the present specification, the ‘selectivity (%)’ is defined as avalue obtained by dividing the change amount of butadiene by the changeamount of butene. For example, the selectivity may be represented by thefollowing equation.Selectivity (%)=[(the number of moles of 1,3-butadiene or COxproduced)/(the number of moles of butene reacted)]×100

In the present specification, the ‘hot spot of a catalyst’ means a placewhere the temperature on the catalyst is the highest in the reactor.

An exemplary embodiment of the present specification comprises: (A)mixing a ferrite-based catalyst molded article with diluent materialparticles; and (B) filling a catalyst reactor with a mixture of theferrite-based catalyst molded article and the diluent materialparticles.

Further, an exemplary embodiment of the present specification provides amethod for filling a catalyst, the method comprising filling at least apartial section in the catalyst reactor, such that the ratio of theweight of the ferrite-based catalyst molded article to the sum of theweights of the ferrite-based catalyst molded article and the diluentmaterial particles is 10 wt % to 15 wt %.

A ferrite-based catalyst may be used in an oxidative dehydrogenationreaction of butene. The oxidative dehydrogenation reaction is anexothermic reaction, and an increase in COx selectivity and a decreasein butadiene selectivity occur due to the exotherm of the ferrite-basedcatalyst. Accordingly, a technology of controlling exotherm by dilutingthe ferrite-based catalyst with an inactive material is known.

However, the related art has an effect of decreasing the amount of heatgenerated by a catalyst reaction, but as the reaction time elapses,there occurs a phenomenon in which a hot spot of the catalyst moves tothe rear side of the reactor in a longitudinal direction, and thereaction temperature needs to be increased to maintain the position ofthe hot spot.

The movement of the hot spot of the catalyst is associated with theinactivity of the catalyst, and there is a problem in that the increasein reaction temperature causes an increase in process costs.

Accordingly, the present inventors could adjust the dilution ratio of acatalyst molded article in a catalyst reactor by using the catalystreactor which is filled by mixing diluent material particles with thecatalyst molded article instead of diluting the catalyst itself. As aresult, the present inventors secured the stability of operation bysimultaneously controlling the hot spot movement rate of a catalystwithin a range capable of controlling exotherm caused by a catalystreaction, and could reduce costs because the reaction temperature doesnot need to be increased. Further, the present inventors could reducethe hot spot movement rate by limiting the concentration of the catalystin a section where an oxidative dehydrogenation reaction starts.

In addition, when a catalyst itself is diluted with a binder materialand the like, the catalyst itself is embedded in the molded article,thereby significantly reducing a catalyst area in which an actualreactant may be brought into contact with the catalyst. However, sincethe method for filling a catalyst according to the present inventionuses a catalyst molded article itself as it is, the surface of thecatalyst introduced may be totally brought into contact with thereactant. Accordingly, the dilution ratio in the catalyst reactor may beeasily adjusted to control the hot spot movement rate.

According to an exemplary embodiment of the present specification, thecatalyst reactor may be filled with a ferrite-based catalyst moldedarticle and diluent material particles, such that the dilution ratios ofthe top and the bottom in the catalyst reactor are different from eachother.

According to an exemplary embodiment of the present specification, in atleast a section in the catalyst reactor, the ratio of the weight of theferrite-based catalyst molded article to the sum of the weights of theferrite-based catalyst molded article and the diluent material particlesmay be 10 wt % to 15 wt %. Preferably, the ratio may be 10 wt % to 13 wt%. When the ratio of the weight of the catalyst molded article in atleast a section in the catalyst reactor is within the above range, thehot spot movement rate of the catalyst may be decreased during theoxidative dehydrogenation reaction of butene.

In particular, according to an exemplary embodiment of the presentspecification, a section where a reaction in the catalyst reactor startsmay be filled such that the ratio of the weight of the ferrite-basedcatalyst molded article to the sum of the weights of the ferrite-basedcatalyst molded article and the diluent material particles is 10 wt % to15 wt %, and the entire section in the catalyst reactor may be filled,such that the ratio of the weight of the ferrite-based catalyst moldedarticle as compared to the sum of the weights of the ferrite-basedcatalyst molded article and the diluent material particles is 10 wt % to15 wt %. As described above, according to an exemplary embodiment of thepresent specification, the hot spot movement rate may be decreased bycontrolling the concentration of a catalyst as compared to a diluentmaterial in a section of the catalyst reactor where a reaction starts.

According to an exemplary embodiment of the present specification, thesection of the catalyst reactor where the reaction starts may mean thetop of the reactor, that is, a section where a reactant of the oxidativedehydrogenation reaction flows in, and thus reacts in the presence ofthe catalyst. A section where the reaction terminates may mean thebottom of the reactor, that is, a bottom portion where the reactant ofthe oxidative dehydrogenation reaction has been flown down from the topafter the reaction is completed.

According to an exemplary embodiment of the present specification, theentire section of the catalyst reactor may mean a region from a sectionof a catalyst reactor where a reaction starts to a section thereof wherethe reaction terminates, and specifically, may mean a region where thecatalyst in the reactor is filled.

According to an exemplary embodiment of the present specification, fromthe section of the catalyst reactor where the reaction starts to thesection thereof where the reaction terminates, the ratio of the weightof the ferrite-based catalyst molded article in the entire section maybe uniform.

According to an exemplary embodiment of the present specification, thefact that the ratio of the weight of the ferrite-based catalyst moldedarticle is made to be uniform may mean that the ratio of the weight ofthe ferrite-based catalyst molded article measured in any region in thecatalyst reactor is the same.

According to an exemplary embodiment of the present specification, theferrite-based catalyst may mean a ferrite-based catalyst prepared by aco-precipitation method. The co-precipitation method may comprise:co-precipitating a metal precursor and a basic aqueous solution;filtering a precipitate; drying the precipitate; and firing theprecipitate.

In an exemplary embodiment of the present specification, theferrite-based catalyst may be represented by the following Formula 1.AFe₂O₄  [Formula 1]

In Formula 1, A is Cu, Ra, Ba, Sr, Ca, Cu, Be, Zn, Mg, Mn, Co, or Ni.

According to an exemplary embodiment of the present specification, theferrite-based catalyst may be a zinc ferrite catalyst.

According to an exemplary embodiment of the present specification, themetal precursor may be a zinc precursor, a ferrite precursor, amanganese precursor, or the like, but is not limited thereto as long asthe metal precursor is typically used. Further, the metal precursor maybe one or more selected from the group consisting of nitrate, ammoniumsalt, sulfate, and chloride, or a hydrate thereof.

According to an exemplary embodiment of the present specification, whenthe ferrite-based catalyst is a zinc ferrite catalyst, the ferrite-basedcatalyst may be prepared by a co-precipitation method of bringing a zincprecursor and a ferrite-based precursor into contact with a basicaqueous solution.

According to an exemplary embodiment of the present specification, thezinc precursor may be zinc chloride (ZnCl₂).

According to an exemplary embodiment of the present specification, theferrite-based precursor may be ferric chloride hydrate (FeCl₃·6H₂O).

According to an exemplary embodiment of the present specification, a pHof the basic aqueous solution may be 7 to 11. Specifically, a pH of thebasic aqueous solution may be more than 7 and 11 or less. Morespecifically, a pH of the basic aqueous solution may be 8 to 11. Whenthe pH of the basic aqueous solution satisfies the above range, there isan effect of stably producing a metal composite catalyst.

According to an exemplary embodiment of the present specification, thebasic aqueous solution may be one or more selected from the groupconsisting of potassium hydroxide, ammonium carbonate, ammoniumbicarbonate, an aqueous sodium hydroxide solution, an aqueous sodiumcarbonate solution, and ammonium water. Preferably, the basic aqueoussolution may be ammonia water.

According to an exemplary embodiment of the present specification, thedrying of the precipitate may be performed before firing theprecipitate, after the precipitate is filtered, and then subjected to awashing step.

According to an exemplary embodiment of the present specification, thedrying of the precipitate may be performed in an oven at 80° C. to 150°C.

According to an exemplary embodiment of the present specification, thefiring of the precipitate may be a step of increasing the temperature upto 650° C. at a rate of 1° C./min, and then firing the precipitate for 6hours. The firing method may be a heat treatment method typically usedin the art.

According to an exemplary embodiment of the present specification, thefiring of the precipitate may be performed by injecting air at 1 L/mininto a firing furnace.

According to an exemplary embodiment of the present specification, theferrite-based catalyst may form a ferrite-based catalyst molded articleby using an extruder.

According to an exemplary embodiment of the present specification, theferrite-based catalyst molded article may be molded in the form of apellet type, a ball type, or a hollow type.

According to an exemplary embodiment of the present specification, thepellet may have a diameter of 1 mm to 5 mm, or 1.5 mm to 3 mm. When thediameter of the pellet satisfies the above range, the exotherm of thecatalyst may be controlled and the activity of the catalyst may beimproved.

According to an exemplary embodiment of the present specification, afinal ferrite-based catalyst molded article may be prepared by moldingthe ferrite-based catalyst into a pellet, and then sintering theferrite-based catalyst.

According to an exemplary embodiment of the present specification, thediluent material particle may be a metal oxide. The metal oxide may bean oxide of one or more metals selected from the group consisting ofzinc (Zn), ferrite (Fe), manganese (Mn), aluminum (Al), cobalt (Co),copper (Cu), radium (Ra), barium (Ba), strontium (Sr), calcium (Ca), andberyllium (Be), but is not limited thereto.

According to an exemplary embodiment of the present specification, thediluent material particle may be an aluminum oxide.

According to an exemplary embodiment of the present specification, thediluent material particle may be alpha aluminum oxide (α-Al₂O₃).

According to an exemplary embodiment of the present specification, thediluent material particle may be a ball type having a diameter of 1 mmto 5 mm, or a ball type having a diameter of 2 mm to 3 mm. When thediameter of the diluent material particles satisfies the above range,the catalyst may be diluted at a desired ratio without hindering theactivity of the catalyst during the mixing of the catalyst moldedarticle, so that it is possible to decrease the hot spot movement rateof the catalyst. The diluent material particle may be not only a balltype, but other various types.

According to an exemplary embodiment of the present specification, thestep (A) may comprise mixing 15 cc to 25 cc of the catalyst moldedarticle with 120 cc to 140 cc of the diluent material particles.

According to an exemplary embodiment of the present specification, whenthe content of the catalyst molded article and the diluent materialparticles is within the above range, at the time of filling the catalystreactor with the catalyst molded article and the diluent materialparticles, the content may be adjusted, such that the ratio of theweight of the catalyst molded article to the total weight of thecatalyst molded article mixed with the diluent material particles is 10wt % to 15 wt %.

Another exemplary embodiment of the present specification provides amethod for preparing butadiene, the method comprising: filling acatalyst reactor with a catalyst according to the above-described methodfor filling a catalyst; and preparing butadiene by subjecting a rawmaterial comprising butene to oxidative dehydrogenation reaction in thecatalyst reactor.

According to an exemplary embodiment of the present specification, thehot spot movement rate of the catalyst of the oxidative dehydrogenationreaction may be 0 to 0.5 mm/hr, 0.00001 mm/hr to 0.3 mm/hr, or 0.01mm/hr or more and less than 0.2 mm/hr. The movement of the hot spot ofthe catalyst is associated with the inactivity of the catalyst, and theincrease in reaction temperature may incur a problem in that an increasein process costs is caused. Accordingly, according to an exemplaryembodiment of the present specification, when the hot spot movement rateof the catalyst of the oxidative dehydrogenation reaction satisfies theabove numerical range, it is possible to obtain an effect of reducingoperation costs due to the low inactivity rate of the catalyst.

Further, an exemplary embodiment of the present specification provides acatalyst reactor which is filled with a mixture of a ferrite-basedcatalyst molded article and diluent material particles.

In addition, an exemplary embodiment of the present specificationprovides a catalyst reactor in which the ratio of the weight of thecatalyst molded article to the total weight of the catalyst moldedarticle mixed with the diluent material particles is 10 wt % to 15 wt %in at least a section in the catalyst reactor.

According to an exemplary embodiment of the present specification, theratio of the weight of the catalyst molded article to the total weightof the catalyst molded article mixed with the diluent material particlesmay be 10 wt % to 13 wt %.

In particular, according to an exemplary embodiment of the presentspecification, in a section where a reaction in the catalyst reactorstarts, the ratio of the weight of the ferrite-based catalyst moldedarticle to the sum of the weights of the ferrite-based catalyst moldedarticle and the diluent material particles may be 10 wt % to 15 wt %,and in the entire section in the catalyst reactor, the ratio of theweight of the ferrite-based catalyst molded article to the sum of theweights of the ferrite-based catalyst molded article and the diluentmaterial particles may be 10 wt % to 15 wt %. When the ratio of theweight of the catalyst molded article in the entire section of thecatalyst reactor is within the above range, the hot spot movement rateof the catalyst may be decreased during the oxidative dehydrogenationreaction of butene.

Furthermore, another exemplary embodiment of the present specificationprovides a method for preparing butadiene, the method comprisingpreparing butadiene by subjecting a raw material comprising butene tooxidative dehydrogenation reaction in the above-described catalystreactor.

According to an exemplary embodiment of the present specification, thepreparing of the butadiene may use a reactant comprising a C₄ mixture.The C₄ mixture comprises one or more normal butenes selected from2-butene (trans-2-butene, cis-2-butene) and 1-butene as an example, andselectively, may further comprise normal butane or C₄ raffinate-3. Thereactant may further comprise one or more selected from air, nitrogen,steam, and carbon dioxide as an example, and preferably, furthercomprises nitrogen and steam. As a specific example, the reactant maycomprise the C₄ mixture, oxygen, steam, and nitrogen at a mol ratio of1:0.1 to 1.5:1 to 15:0.5 to 10 or 1:0.5 to 1.2:5 to 12:0.5 to 5.Furthermore, the method for preparing butadiene according to anexemplary embodiment of the present specification has an advantage inthat the reaction efficiency is excellent and waste water is generatedin a small amount even though steam is used in a small amount of 1 to 10or 5 to 10 mol based on 1 mol of the C₄ mixture, and ultimately providesan effect of reducing not only waste water treatment costs, but alsoenergy consumed for the process. The oxidative dehydrogenation reactionmay be performed, for example, at a reaction temperature of 250 to 500°C., 300 to 450° C., 320 to 400° C., 330 to 380° C., or 350 to 370° C.,and within this range, the reaction efficiency is excellent withoutsignificantly increasing the energy costs, so that 1,3-butadiene may beprovided with high productivity.

According to an exemplary embodiment of the present specification, thepreparing of the butadiene is performed under conditions of a reactiontemperature of 360° C. and a gas hourly space velocity (GHSV) of 120 h⁻¹in a single reactor, and the reactant may comprise the C₄mixture:oxygen:steam:nitrogen at a mol ratio of 1:0.67:5:2.67.

As described above, the method for filling a catalyst according to anexemplary embodiment of the present specification may fill a catalyst bymixing a ferrite-based catalyst molded article used for an oxidativedehydrogenation reaction with diluent material particles and constantlyadjust the ratio of the weight of the catalyst molded article to thetotal weight of the catalyst molded article mixed with the diluentmaterial particles in the entire section of the catalyst reactor,thereby controlling exotherm and simultaneously decreasing the hot spotmovement rate of the catalyst.

EXAMPLES

Hereinafter, the present specification will be described in detail withreference to Examples for specifically describing the presentspecification. However, the Examples according to the presentspecification may be modified in various forms, and it is notinterpreted that the scope of the present specification is limited tothe Examples described below in detail. The Examples of the presentspecification are provided to more completely explain the presentspecification to a person with ordinary skill in the art.

EXAMPLES <Preparation Example> Preparation of Catalyst

1) Preparation of Metal Oxide

A metal precursor solution was prepared by dissolving 12.019 g of zincchloride (ZnCl₂) and 47.662 g of ferric chloride (FeCl₃) in 155.59 g ofdistilled water. In this case, for a mol ratio of the metal componentscomprised in the metal precursor solution, Zn:Fe=1:2. An aqueous ammoniasolution was added dropwise to the prepared aqueous metal precursorsolution such that the pH was 9, and the resulting mixture was stirredfor 1 hour and co-precipitated. Thereafter, a co-precipitate wasobtained by filtering the co-precipitation solution under reducedpressure, and after the co-precipitate was dried at 90° C. for 16 hours,the temperature was increased up to 650° C. from 80° C. at a warmingrate of 1° C./min under an air atmosphere, a zinc-iron oxide (ZnFe₂O₄)powder having a spinel structure was prepared by maintaining thetemperature for 6 hours.

2) Preparation of Pellet Catalyst for Oxidative Dehydrogenation Reaction

After the prepared metal oxide powder was ground to 0.6 mm to 0.85 mm, amixture of isopropyl alcohol with water as a liquid binder wasintroduced into the powder, and then the resulting product was uniformlykneaded by using a kneader, and the kneaded product was molded into acylindrical pellet having a diameter of 1.5 mm to 3 mm, a circular crosssection, and a height of 1.5 mm to 9 mm by using an extrusion moldingmachine. The molded pellet was dried at 90° C. for 12 hours andheat-treated at 500° C. for 4 hours.

Example 1

130 cc of an α-Al₂O₃ ball having a diameter of 2 mm to 3 mm was mixedwith 20 cc of the ferrite-based catalyst molded article prepared inPreparation Example 1, and a reactor was filled with the mixture, suchthat the ratio of the catalyst molded article was 10.17 wt % in theentire section of the reactor.

Example 2

125 cc of an α-Al₂O₃ ball having a diameter of 2 mm to 3 mm was mixedwith 25 cc of the ferrite-based catalyst molded article prepared inPreparation Example 1, and a reactor was filled with the mixture, suchthat the ratio of the catalyst molded article was 13.00 wt % in theentire section of the reactor.

Example 3

The reactor was filled with 20 cc of the ferrite-based catalyst moldedarticle prepared in Preparation Example 1 and 130 cc of the α-Al₂O₃ ballhaving a diameter of 2 mm to 3 mm by varying the ratio of the top andthe bottom of the reactor as in the following Table 1. In this case, theratio of the catalyst in a section (top) of the reactor where thereaction started was 3.65 wt %.

TABLE 1 Reactor Catalyst (cc) α-Al₂O₃ (cc) 1 (Top) 0.33 13 2 0.33 13 30.67 13 4 0.67 13 5 1 13 6 2 13 7 3 13 8 4 13 9 4 13 10 (Bottom) 4 13

Example 4

105 cc of an α-Al₂O₃ ball having a diameter of 2 mm to 3 mm was mixedwith 45 cc of the ferrite-based catalyst molded article prepared inPreparation Example 1, and a reactor was filled with the mixture, suchthat the ratio of the catalyst molded article was 25 wt % in the entiresection of the reactor.

Comparative Example 1

After 2) the preparation of the catalyst for an oxidativedehydrogenation reaction in Preparation Example 1, 180 g of acommercially available alumina silicate support was coated with 17.8 gof the catalyst to mold the resulting product such that the ratio of thecatalyst to the total weight of the ferrite-based catalyst moldedarticle was 9 wt %.

A reactor was filled with 150 cc of the obtained ferrite-based catalystmolded article without any additional dilution.

Comparative Example 2

The entire section of the reactor was filled with the catalyst moldedarticle without mixing 150 cc of the ferrite-based catalyst moldedarticle prepared in Preparation Example 1 with a diluent material.

Experimental Example

The results of subjecting a raw material comprising butene to oxidativedehydrogenation reaction in each of the reactors in Examples 1 to 4 andComparative Examples 1 and 2, and measuring the hot spot movement rate,the conversion rate of butene, the butadiene selectivity, the COxselectivity, and the change in temperature of the hot spot are shown inthe following Table 2.

The preparing of the butadiene by the oxidative dehydrogenation reactionwas performed under conditions of a reaction temperature of 360° C. anda gas hourly space velocity (GHSV) of 120 h⁻¹ in a single reactor, andthe reactant comprised the C₄ mixture oxygen:steam:nitrogen at a molratio of 1:0.67:5:2.67.

TABLE 2 Ratio of catalyst in the Butene section where Hot spot movementconversion Butadiene COx Hot spot the reaction rate rate selectivityselectivity temperature Classification starts (wt %) (mm/hr) (%) (%) (%)(° C.) Example 1 10.17 4 mm/ 0.10 81.7 84.2 13.9 511 38.26 hr Example 213.00 2 mm/ 0.13 80.4 85.1 13.4 513 15.05 hr Example 3 3.65 20 mm/ 0.5288.2 86.3 11.8 458 38.62 hr Example 4 25 14 mm/ 0.49 77.2 83.7 13.9 52528.60 hr Comparative 9.00 12 mm/ 1.25 69.5 89.4 8.5 437 Example 1 9.59hr Comparative 100.00 10 mm/ 0.20 76.2 81.5 16.1 571 Example 2 49.21 hr

According to Table 2, it can be confirmed that in the case of anoxidative dehydrogenation reaction of butene in a catalyst reactor whichis filled with a mixture of the catalyst molded article with the diluentmaterial particles according to Example 1, the hot spot movement rate isdecreased.

When Example 1 is compared with Comparative Example 1, it can beconfirmed that in Example 1 in which the catalyst molded article is usedas it is and the ratio of the catalyst of the reactor is adjusted byusing the diluent material particles, the hot spot movement rate isdecreased to 8/100 or less, and the conversion rate of butene isimproved as compared to Comparative Example 1 in which a catalyst moldedarticle diluted by coating a support with the catalyst itself is used.

In addition, when Example 1 is compared with Comparative Example 2, itcan be confirmed that in Example 1 in which the catalyst molded articleis used as it is and the ratio of the catalyst of the reactor isadjusted by using the diluent material particles, the hot spot movementrate is decreased to ½ or less as compared to Comparative Example 2 inwhich a catalyst which is not mixed with a diluent material is used.

When Example 1 is compared with Examples 3 and 4, it can be seen thatwhen the reactor is filled such that the ratio of the catalyst in thesection where the reaction starts is 10 wt % to 15 wt %, a better effectcan be obtained.

Consequently, the method for filling a catalyst according to the presentspecification may ultimately decrease the hot spot movement rate of thecatalyst by adjusting the ratio of the catalyst to a specific ratio inthe entire section of the catalyst reactor where the oxidativedehydrogenation reaction occurs, particularly, a section where thereaction starts.

Although the preferred exemplary embodiments of the present inventionhave been described above, the present invention is not limited thereto,and various modifications can be made and carried out within the scopeof the claims and the detailed description of the invention, and alsofall within the scope of the invention.

The invention claimed is:
 1. A method of feeding a catalyst reactor forpreparation of butadiene comprising: (A) mixing a ferrite-based catalystmolded article with diluent material particles to form a mixture,wherein the ferrite-based catalyst is a zinc ferrite and the diluentparticles are α-Al₂O₃; and (B) adding the mixture of the ferrite-basedcatalyst molded article and the diluent material particles to a catalystreactor.
 2. The method of claim 1, wherein at least a section in thecatalyst reactor is filled, such that a ratio of a weight of theferrite-based catalyst molded article to a sum of the weights of theferrite-based catalyst molded article and the diluent material particlesis 10 wt % to 15 wt %.
 3. The method of claim 2, wherein a section ofthe catalyst reactor where the reaction starts is filled, such that theratio of the weight of the ferrite-based catalyst molded article ascompared to the sum of the weights of the ferrite-based catalyst moldedarticle and the diluent material particles is 10 wt % to 15 wt %.
 4. Themethod of claim 2, wherein an entire section of the catalyst reactor isfilled, such that the ratio of the weight of the ferrite-based catalystmolded article to the sum of the weights of the ferrite-based catalystmolded article and the diluent material particles is 10 wt % to 15 wt %.5. The method of claim 1, wherein the ferrite-based catalyst moldedarticle is molded in a form of a pellet type, a ball type, or a hollowtype.
 6. The method of claim 5, wherein the ferrite-based catalystmolded article is molded in a form of a pellet type, and the pellet hasa diameter of 1 mm to 5 mm.
 7. The method of claim 1, wherein thediluent material particle is a ball type having a diameter of 1 mm to 5mm.
 8. The method of claim 1, further comprising: preparing butadiene bysubjecting a raw material comprising butene to an oxidativedehydrogenation reaction in the catalyst reactor.
 9. The method of claim8, wherein a hot spot movement rate of the catalyst of the oxidativedehydrogenation reaction is 0 to 0.5 mm/hr.
 10. The method of claim 1,further comprising forming the ferrite-based catalyst molded article,the forming comprising: preparing a powder comprising zinc ferrite,molding the powder to form a molded zinc ferrite body, and sintering themolded zinc ferrite body to form the ferrite-based catalyst moldedarticle; and wherein the diluent particles are mixed with theferrite-based catalyst molded article subsequent to the forming.